The use of magnetic disks for the storage of computer readable data is well known in the art. Magnetic disks may be fixed in a drive or may be removable. An optical disk is a data storage medium which is readable by a laser-based reading device. Optical disks such as "compact disks" ("CDs") are commonly used for storing musical and audio-visual works. Due to the huge storage capacity of optical disks as compared to conventional magnetic storage media, optical disks are also used in the computer industry. One type of optical disk, a magneto-optical disk, can be readily written and erased and is thus becoming increasingly popular to complement or replace conventional magnetic disks ("hard disks" and "floppy disks"). To increase storage capacity, optical disks may have the ability to store data on both sides of the disk.
To facilitate storing and handling of removable optical disks and magnetic disks, the disks are normally mounted in parallelepiped-shaped cartridges. Also used in the computer industry for data storage are parallelepiped-shaped tape cartridges such as Digital Audio Tape (DAT) cartridges and 8-mm tape cartridges.
For large databases consisting of many disk or tape cartridges, it is necessary to provide a system for storing and handling the cartridges. Various features and components of cartridge storing and handling systems, generally referred to in the art are "autochangers", are disclosed in U.S. Pat. Nos. 4,998,232 issued Mar. 5, 1991 for OPTICAL DISK HANDLING APPARATUS WITH FLIP LATCH of Methlie et al. (and corresponding EPO patent application no. 89312226.7 filed Nov. 24, 1989); 5,014,255 issued May 7, 1991 for OPTICAL DISK CARTRIDGE HANDLING APPARATUS WITH PASSIVE CARTRIDGE ENGAGEMENT ASSEMBLY of Wanger et al. (and corresponding EPO patent application No. 90300988.4 filed Jan. 31, 1990; 5,010,536 issued Apr. 23, 1991 for CARTRIDGE HANDLING SYSTEM of Wanger et al. (and corresponding EPO patent application No. 90301420.7 filed Feb. 9, 1990; 5,043,962 issued Aug. 27, 1991 for CARTRIDGE HANDLING SYSTEM of Wanger et al. (and corresponding EPO patent application No. 90302635.9 filed Mar. 13, 1990); 5,062,093 issued Oct. 29, 1991 for OPTICAL DISK INSERTION APPARATUS of Christie et al. (and corresponding EPO patent application No. 89312461.0 filed Nov. 30, 1989); 5,101,387 issued Mar. 31, 1992 for LATERAL DISPLACEMENT CONTROL ASSEMBLY FORAN OPTICAL DISK HANDLING SYSTEM of Wanger et al. (and corresponding EPO patent application No. 90300305.1 filed Jan. 11, 1990); 5,184,336 issued Feb. 2, 1993 for LATERAL DISPLACEMENT CONTROL ASSEMBLY FOR AN OPTICAL DISK HANDLING SYSTEM of Wanger et al.; co-pending U.S. patent application Ser. No. 08/020,160 filed Feb. 18, 1993 for LINEAR DISPLACEMENT AND SUPPORT APPARATUS FOR USE IN A CARTRIDGE HANDLING SYSTEM of Luffel et al., and co-pending U.S. patent application Ser. No. 08/135,607 filed Oct. 12, 1993 for CARTRIDGE HANDLING SYSTEM WITH DUAL CARTRIDGE ENGAGING ASSEMBLY of Rugg et al., which are each hereby specifically incorporated by reference for all that is disclosed therein.
In general, a media autochanger may include a media storage system for storing media such as optical disk cartridges at predetermined storage locations. Such an autochanger may perform such functions as retrieving a desired cartridge from its storage location, transporting the cartridge to a disk or tape drive, and inserting the cartridge into the drive. The media autochanger may also perform the functions of removing a cartridge from a drive, moving the cartridge into alignment with its original or other storage location, and inserting the cartridge in that storage location. It may also be necessary for the autochanger to flip a cartridge before insertion or reinsertion into a drive to reverse the side thereof which is read or written by the drive.
Methlie et al. U.S. Pat. 4,998,232 incorporated by reference above, discloses an autochanger having a media holding assembly which is rotatable about a longitudinally extending flip axis. The media holding assembly has a first rotational registration position and a second rotational registration position which is angularly displaced 180.degree. from the first registration position. In the two registration positions, the media holding assembly is positioned in angular alignment with associated media drives or storage slots and may thus be oriented to insert media into the associated drive or storage slot with the media in a first side up orientation or a second side up orientation depending upon the rotational registration position of the media holder.
The media holding assembly may be rotated about the longitudinal flip axis, from one rotational registration position to the other, by an associated drive motor. A flip-latch assembly is provided to selectively terminate rotation of the holding assembly at each rotational registration position and to maintain the holding assembly in that registration position until the flip-latch assembly is selectively tripped.
The flip-latch assembly of U.S. Pat. No. 4,998,232 includes a pair of longitudinally extending projections which extend from a longitudinal end portion of the holding assembly. The flip-latch assembly also includes a latching assembly mounted on a stationary frame member positioned immediately to the rear of the media holding assembly. The latching assembly engages a different longitudinally extending projection on the media holding assembly when the holding assembly is in each of the rotational registration positions.
A longitudinally extendable and retractable media engaging member is mounted with in the holding assembly and is used to engage a media unit, typically a cartridge, positioned in front of the holding assembly and to pull the engaged cartridge into the holding assembly for subsequent transport to a new storage location. The media engaging member is thereafter used to push the cartridge out of the holding assembly into the new storage location or drive. A longitudinally rearwardly extending projection mounted on the media engaging member is positioned such that as the cartridge engaging member moves to its rearwardmost position, this extension on the media engaging member trips the latch assembly, i.e., contacts and moves a portion of the latch assembly in a manner so as to unlatch the projection on the holding assembly and allow the holding assembly to rotate.
Applicants have discovered problems with the flip-latch arrangement described in Methlie et al. Due to the use of a latching assembly mounted to the rear of the media holding assembly and longitudinally extending latch engageable projections on the media holding assembly and longitudinally extending latch tripping projections on the cartridge engaging member, extremely close longitudinal tolerances must be maintained in all of the associated system components, e.g., between the media holding assembly and the engaging member, between the media holding assembly and the frame member where the latching assembly is mounted, between the latching assembly and the frame on which it is mounted, as well as the longitudinal dimensions of the projections on the holding assembly and the media engaging member. If such close tolerances are not maintained then malfunctions may occur. For example, the projection on the holding assembly may not properly contact the latch assembly causing it to bounce out of the latch assembly. High precision is also required in and between components in the circumferential direction because of the radical inward location of the latch assembly. If precision of dimensions in the circumferential direction is not maintained, then the registration position of the holding assembly may be angularly misaligned with associated cartridge drives or storage bays leading, again, to system malfunctions.